The 48-year-old's status is a reversal from an earlier statement by Yandex that announced his death. He is in fact on life support with "no sign of brain activity," according to the company.
Segalovich had been diagnosed with a treatable form of cancer and "was responding well to treatment and working a full schedule" before things took a turn for the worse, according to Yandex.
Segalovich and chief executive Arkady Volozh co-founded the business more than 20 years ago by offering software that allowed people to search through the Bible on compact discs. In 1997, the pair started the Yandex.ru Internet search engine, which now controls more than 60 percent of the Russian market.